CN117925217A

CN117925217A - Quantum dot composite structure and forming method thereof

Info

Publication number: CN117925217A
Application number: CN202211430423.8A
Authority: CN
Inventors: 刘擎; 黄文泽; 刘如熹; 严珮璁; 谢佳纯; 童鸿钧; 李育群; 蔡宗良
Original assignee: Lextar Electronics Corp
Current assignee: Lextar Electronics Corp
Priority date: 2022-10-17
Filing date: 2022-11-08
Publication date: 2024-04-26
Also published as: US20240124350A1; TWI831419B

Abstract

Quantum dot composite structures and methods of forming the same are provided. The quantum dot composite structure comprises glass particles and an inorganic protective layer. The glass particles include a glass matrix and a plurality of quantum dots positioned in the glass matrix, and the glass matrix exposes an exposed surface of at least one of the plurality of quantum dots. The inorganic protective layer is arranged on the glass particles and covers the exposed surface.

Description

Quantum dot composite structure and forming method thereof

Technical Field

The present invention relates to a quantum dot composite structure and a method for forming the same, and more particularly, to a quantum dot composite structure with a protective layer and a method for forming the same.

Background

Due to quantum confinement effect, the emission spectrum can be regulated by the particle size, and has a narrow full WIDTH AT HALF maximum width (FWHM) characteristic, and can provide high-purity chromatic light. Quantum dots are widely used, for example, in the fields of light emitting diodes, lighting, solar cells, biomarkers, displays, and the like.

However, the quantum dots are often affected by moisture and/or oxygen in the environment, so that the stability of the quantum dots is reduced, thereby reducing the light emitting effect. Thus, while existing quantum dots and methods of forming them have gradually met their intended use, they have not been completely satisfactory in all respects. Accordingly, there are still some problems to be overcome with respect to quantum dots and methods of forming the same.

Disclosure of Invention

In some embodiments, a quantum dot composite structure is provided. The quantum dot composite structure comprises glass particles and an inorganic protective layer. The glass particles include a glass matrix and a plurality of quantum dots positioned in the glass matrix, and the glass matrix exposes an exposed surface of at least one of the plurality of quantum dots. The inorganic protective layer is arranged on the glass particles and covers the exposed surface.

In some embodiments, methods of forming quantum dot composite structures are provided. The method for forming the quantum dot composite structure comprises the steps of providing glass particles, wherein the glass particles comprise a plurality of quantum dots; forming a first protective layer on the glass particles through an atomic layer deposition process, so that the first protective layer conformally coats the glass particles; and forming a second protective layer on the first protective layer through a sol-gel (sol-gel) process, so that the second protective layer covers the first protective layer.

The quantum dot composite structure and the forming method thereof can be applied to various types of electronic devices. In order to make the features and advantages of the present disclosure more comprehensible, various embodiments accompanied with figures are described in detail below.

Drawings

The aspects of the embodiments of the present disclosure will be better understood from the following detailed description in conjunction with the accompanying drawings. It is noted that some components (features) may not be drawn to scale according to industry standard practices. In fact, the dimensions of the various features may be increased or decreased for clarity of description.

Fig. 1 is a schematic perspective view illustrating a glass block according to some embodiments of the present disclosure.

Fig. 2-4 are schematic perspective views respectively showing different quantum dot composite structures according to some embodiments of the disclosure.

Fig. 5 is an X-ray diffraction analysis (X-ray diffraction analysis, XRD) diagram showing stages in a method of forming a quantum dot composite structure, according to some embodiments of the present disclosure.

Fig. 6 is a fluorescence spectrum showing various stages in a method of forming a quantum dot composite structure, according to some embodiments of the present disclosure.

Fig. 7 and 8 are graphs of hydrophobic test images showing stages in a method of forming a quantum dot composite structure, respectively, according to some embodiments of the present disclosure.

Fig. 9-12 are scanning electron microscope (scanning electron microscope, SEM) images respectively showing stages in a method of forming a quantum dot composite structure, according to some embodiments of the present disclosure.

Fig. 13 is an infrared absorption spectrum (infrared absorption spectrum) showing various stages in a method of forming a quantum dot composite structure, according to some embodiments of the present disclosure.

Fig. 14 and 15 are transmission electron microscope (transmission electron microscopy, TEM) images respectively showing stages in a method of forming a quantum dot composite structure, according to some embodiments of the present disclosure.

Fig. 16 is a schematic diagram of a light emitting diode device according to some embodiments of the present disclosure.

Fig. 17 is a schematic diagram of a light emitting diode device according to some embodiments of the present disclosure.

Detailed Description

The following disclosure provides many different embodiments or examples for implementing different components in the provided quantum dot composite structures. Specific examples of components and arrangements thereof are described below to simplify the present disclosure, but are not, of course, limiting the present disclosure. For example, references to a first element being formed on a second element may include embodiments in which the first element and the second element are in direct contact, and may include embodiments in which additional elements are formed between the first element and the second element such that the first element and the second element are not in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples or embodiments. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or examples discussed.

Directional terms mentioned herein, such as: the terms "upper", "lower", "left", "right" and the like refer to the directions of the drawings. Accordingly, the directional terminology is used to illustrate and not limit the disclosure.

In some embodiments of the present disclosure, terms such as "disposed," "connected," and the like, with respect to an arrangement, connection, and the like, may refer to two elements being in direct contact or may refer to two elements not being in direct contact, unless otherwise specified, with additional junction elements located between the two structures. The terms disposed and connected may also include the case where both structures are movable or where both structures are fixed.

In addition, references to "first," "second," and the like in this specification or in the claims are used for naming different components or distinguishing between different embodiments or ranges, and are not intended to limit the upper or lower limit on the number of components or to limit the order in which the components are manufactured or arranged.

Hereinafter, "about," "substantially," or the like, means within 10%, or within 5%, or within 3%, or within 2%, or within 1%, or within 0.5% of a given value or range of values. Where a given amount is an approximate amount, that is, where "about" or "substantially" is not specifically recited, the meaning of "about" or "substantially" may still be implied.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will be appreciated that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Some variations of the embodiments are described below. In the various drawings and illustrative embodiments, the same or similar reference numerals are used to designate the same or similar components. It is to be understood that additional steps may be provided before, during, and after the method, and that some of the described steps may be substituted or deleted for the other embodiments of the method.

Fig. 1 is a schematic perspective view illustrating a glass block 100' according to some embodiments of the present disclosure. In some embodiments, as shown in fig. 1, a glass block 100 'may include a glass matrix 110 and a plurality of quantum dots 120, in other words, the glass block 100' may be a block having a plurality of quantum dots 120 embedded in the glass matrix 110. In some embodiments, fig. 1 illustrates that the glass block 100' may be rectangular parallelepiped, although the disclosure is not limited thereto. In some embodiments, the glass substrate 110 may be formed by a melt-quench (melt-quench) process. In some embodiments, since the plurality of quantum dots 120 may be embedded in the glass matrix 110, and the glass matrix 110 has rigidity and hydrophobicity, the glass matrix 110 may promote the moisture and oxygen resistance characteristics of the plurality of quantum dots 120, thereby improving stability and reliability.

In some embodiments, the glass matrix 110 may include or may be phosphosilicate glass (phosphosilicate glass), tellurite glass (tellurite glass), borosilicate glass (borosilicate glass), borogermanate glass (borogermanate glass), or any combination thereof, although the disclosure is not limited thereto. In some embodiments, the plurality of quantum dots 120 may include or may be group II-VI, group III-V, group IV-VI, and/or group IV semiconductor materials. In some embodiments, the plurality of quantum dots 120 may include or may be cadmium-based quantum dots such as cadmium sulfide (CdSe), cadmium-free quantum dots such as indium phosphide (InP), quantum dots such as inorganic perovskite (inorganic perovskite), other suitable quantum dots, or any combination thereof. For example, the plurality of quantum dots 120 may be CdSe、CdTe、ZnS、ZnSe、ZnTe、ZnO、HgS、HgSe、HgTe、CdSeS、CdSeTe、CdSTe、ZnSeS、ZnSeTe、ZnSTe、HgSeS、HgSeTe、HgSTe、CdZnS、CdZnSe、CdZnTe、CdHgS、CdHgSe、CdHgTe、HgZnS、HgZnSe、HgZnTe、CdZnSeS、CdZnSeTe、CdZnSTe、CdHgSeS、CdHgSeTe、CdHgSTe、HgZnSeS、HgZnSeTe、HgZnSTe、GaN、GaP、GaAs、GaSb、AlN、AlP、AlAs、AlSb、InN、InP、InAs、InSb、GaNP、GaNAs、GaNSb、GaPAs、GaPSb、AlNP、AlNAs、AlNSb、AlPAs、AlPSb、InNP、InNAs、InNSb、InPAs、InPSb、GaAlNP、GaAlNAs、GaAlNSb、GaAlPAs、GaAlPSb、GaInNP、GaInNAs、GaInNSb、GaInPAs、GaInPSb、InAlNP、InAlNAs、InAlNSb、InAlPAs、InAlPSb、SnS、SnSe、SnTe、PbS、PbSe、PbTe、SnSeS、SnSeTe、SnSTe、PbSeS、PbSeTe、PbSTe、SnPbS、SnPbSe、SnPbTe、SnPbSSe、SnPbSeTe、SnPbSTe、CsPbCl₃、CsPbBr₃、CsPbI₃、Cs₄PbCl₆、Cs₄PbBr₆、Cs₄PbI₆, or CsPbX ₃/Cs₄PbX₆ where X is Cl, br, I. In some embodiments, the quantum dots 120 may emit longer wavelength (low energy) light after excitation by short wavelength (high energy) blue or UV light. In some embodiments, blue light may be provided by blue light emitting diodes and UV light may be provided by UV light emitting diodes. In some embodiments, the quantum dots 120 emit light at wavelengths of greater than or equal to 300nm to less than or equal to 800nm under excitation by blue or UV light.

In some embodiments, glass block 100' is exemplified as a perovskite quantum dot glass block. In some embodiments, the powder of the chemicals described below is weighed according to the following ratio, ground and mixed uniformly to obtain a powder mixture. The ratio is as follows: 25.71 mol (mol)SiO₂、42.55mol B₂O₃、16.12mol ZnO、6.84mol SrCO₃、2.04mol K₂CO₃、1.02mol BaCO₃、0.30mol Sb₂CO₃、2.86mol Cs₂CO₃、5.72mol PbBr₂ and 5.72mol NaBr. Next, the powder mixture was placed in a platinum crucible or an alumina crucible, and fed into a muffle furnace (muffle furnace) to melt the powder mixture at 1200 ℃ for 15 minutes. After the powder mixture was completely melted, the melt was poured onto a brass mold or a graphite mold preheated to 350 ℃ and rapidly fed into a muffle furnace together with the mold to perform an annealing treatment at 350 ℃ for 3 hours to obtain a precursor glass (pre glass) of the glass block 100'. Then, the precursor glass is sent into a muffle furnace to be subjected to heat treatment (HEAT TREATMENT) for 10 hours at 470-570 ℃, so that the perovskite quantum dots 120 are crystallized in the glass substrate 110 to form a glass block 100'.

Fig. 2 shows a schematic perspective view of a quantum dot composite structure 1, according to some embodiments of the present disclosure.

In some embodiments, in order to make the glass block 100 'shown in fig. 1 practical, it is necessary to grind the glass block 100' into glass particles 100 (glass powder) as shown in fig. 2 before applying the glass particles to the light emitting diode package structure or the display. Accordingly, in some embodiments, a polishing process may be performed on the glass block 100 'such that the glass block 100' is broken to be dispersed into a plurality of glass particles 100. In some embodiments, the polishing process may be uniformly polished by a mortar, but the disclosure is not limited thereto.

Then, in some embodiments, a particle size screening process may be performed on the plurality of glass particles 100 to concentrate the particle size distribution of the plurality of glass particles 100. In some embodiments, the average diameter 100d of the glass particles 100 is calculated by taking microscopic images of the glass particles 100 by a scanning electron microscope (scanning electron microscope, SEM) and estimating the diameter values of the respective particles by Image analysis software (such as Image J). In some embodiments, the particle size screening process may include or may be a filtration process, a gravity sedimentation process, a centrifugation process, other suitable screening processes, or a combination thereof, although the disclosure is not limited thereto. In some embodiments, the average diameter 100d of the glass particles 100 may be greater than or equal to 20 μm to less than or equal to 50 μm. For example, the average diameter 100d of the glass particles 100 may be 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, values between the foregoing values, or ranges of values, although the disclosure is not limited thereto. In some embodiments, if the average diameter 100d of the glass particles 100 is greater than 50 μm, the packaging process may not be easily completed, while if the average diameter 100d of the glass particles 100 is less than 20 μm, the glass matrix 110 may be damaged greatly, which may affect the absorption of the excitation light source by the glass particles 100, and thus affect the quantum efficiency, and/or may cause the quantum dots 120 to be closer to or exposed to the surface of the glass particles 100, which may cause the quantum dots 120 to be degraded more easily by moisture or oxygen, and thus affect the quantum efficiency.

In some embodiments, about 2.5g of glass particles 100 may be weighed first, placed in a beaker, and 30mL of ethanol may be added to stir at room temperature such as 25 ℃ for 30 minutes, then stirring is stopped and left to stand for about 2 minutes, after the larger particle size glass particles 100 settle to the bottom, the smaller particle size glass particles 100 are suspended above, and the suspension above is sucked out with a dropper to filter out the smaller particle size glass particles 100, which is repeated a plurality of times until the particle size of the glass particles 100 is 20 μm or more and 50 μm or less, for example, the above steps may be repeated four times to obtain glass particles 100 subjected to the particle size selection process.

In some embodiments, since the glass particles 100 may have an irregular profile after performing the polishing process and the particle size screening process, the glass matrix 110 in the glass particles 100 may expose the exposed surface 120S of at least one of the plurality of quantum dots 120. That is, in the polishing process, the surface layer of the glass particles 100 is easily broken, so that a portion of the surface of the quantum dots 120 is exposed, and the quantum dots 120 are deteriorated by environmental factors such as moisture and/or oxygen.

In order to protect the quantum dots 120 from external substances such as moisture or oxygen, as shown in fig. 2, in some embodiments, an inorganic protective layer 200 is formed on the surface of the glass particles 100 to cover the exposed surfaces 120S of the quantum dots 120, thereby obtaining the quantum dot composite structure 1. Since the inorganic protective layer 200 covers the exposed surface 120S of the quantum dot 120, the inorganic protective layer 200 can improve the moisture resistance, oxygen resistance, hydrophobicity, water resistance and/or application universality of the quantum dot composite structure 1, for example, under a high humidity environment, while maintaining or not affecting the carrier transmission efficiency and/or the light emitting efficiency of the quantum dot 120 in the quantum dot composite structure 1.

In some embodiments, the inorganic protective layer 200 may be a single layer or multiple layers. In some embodiments, the inorganic protective layer 200 may be formed by an atomic layer deposition (atomic layer deposition, ALD) process, a sol-gel (sol-gel) process, other suitable process, or a combination thereof. In some embodiments, the inorganic protective layer 200 may be a single layer or multiple layers formed by an atomic layer deposition process. In this embodiment, the inorganic protective layer 200 conformally (conformally) conforms to the shape of the glass particles and is formed on the surface of the glass particles 100. In other embodiments, the inorganic protective layer 200 may be a single layer or multiple layers formed by a sol-gel process. In this embodiment, the inorganic protective layer 200 is formed on the glass particles 100. In other embodiments, the inorganic protective layer 200 may include different layers formed by an atomic layer deposition process and a sol-gel process, respectively. Since the inorganic protective layer 200 may be formed by an atomic layer deposition process and/or a sol-gel process, the inorganic protective layer 200 can be formed on the glass particles 100 without damaging the internal crystalline structure of the quantum dots 120 in the glass particles 100 at the formation temperature and other formation conditions. Therefore, after the inorganic protective layer 200 is formed, characteristics of the quantum dots 120 such as high color purity (color purity), high quantum efficiency, narrow light emission half-width can be maintained.

In some embodiments, the reaction temperature of the atomic layer deposition process and/or the sol-gel process may be greater than or equal to 60 ℃ to less than or equal to 180 ℃. For example, the reaction temperature of the atomic layer deposition and/or sol-gel process may be 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃, 180 ℃, or a range between the foregoing values, although the disclosure is not limited thereto. In some embodiments, the reaction temperature of the atomic layer deposition process may be greater than or equal to 75 ℃ to less than or equal to 90 ℃. In some embodiments, the reaction temperature of the sol-gel process may be greater than or equal to 75 ℃ to less than or equal to 90 ℃.

In some embodiments, the inorganic protective layer 200 may include or may be an inorganic oxide (inorganic oxide), although the disclosure is not limited thereto. In some embodiments, the inorganic protective layer 200 may include or may be titanium oxide (TiO ₂), silicon oxide (SiO ₂), aluminum oxide (Al ₂O₃), zirconium oxide (ZrO ₂), other suitable oxides, or any combination thereof, although the disclosure is not limited thereto. In some embodiments, the inorganic protective layer 200 may include multiple layers, and the multiple layers include the same material formed by different processes, wherein the multiple layers include the same material, but have different characteristics due to different forming processes. For example, the inorganic protective layer 200 may include silicon oxide formed by an atomic layer deposition process and silicon oxide formed by a sol-gel process.

In some embodiments, the thickness 200t of the inorganic protective layer 200 may be greater than or equal to 1nm to less than or equal to 500nm. For example, the thickness 200t of the inorganic protective layer 200 may be 1nm, 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, a value or a range of values between the foregoing values, but the disclosure is not limited thereto. In some embodiments, if the thickness 200t of the inorganic protection layer 200 is greater than 500nm, the problems of reduced carrier transport efficiency and poor light emitting efficiency of the quantum dots 120 may be caused, and if the thickness 200t of the inorganic protection layer 200 is less than 1nm, the quantum dots 120 may not be effectively protected from degradation due to environmental factors. In some embodiments, the average diameter d of the quantum dot composite structure 1 containing the inorganic protective layer 200 may be greater than or equal to 20.002 μm to less than or equal to 51 μm. For example, the average diameter d of the quantum dot composite structure 1 may be 21 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 51 μm, a value or a range of values between the foregoing values, but the disclosure is not limited thereto.

In some embodiments, the inorganic protective layer 200 may be composed of multiple layers, and the total thickness of the multiple layers is not more than 500nm, so as to avoid the problem of poor light-emitting efficiency and reduced carrier transport efficiency of the quantum dots caused by excessive thickness.

For ease of description, the same or similar reference numerals are not repeated.

Fig. 3 is a schematic perspective view illustrating a quantum dot composite structure 2 according to some embodiments of the present disclosure. As shown in fig. 3, in some embodiments, the inorganic protective layer 200 of the quantum dot composite structure 2 may include a first protective layer 210 and a second protective layer 220. In some embodiments, the first protective layer 210 may encapsulate the glass particles 100, and the first protective layer 210 is in direct contact with the exposed surface 120S of the quantum dot 120. In some embodiments, the first protective layer 210 conforms to the shape of the glass particle 100 (shape), i.e., the first protective layer 210 conforms to the shape of the glass particle 100 and is formed on the surface of the glass particle 100. In some embodiments, the second protective layer 220 may be disposed on the first protective layer 210, and the first protective layer 210 may be interposed between the glass particles 100 and the second protective layer 220. In some embodiments, the second protective layer 220 encapsulates the first protective layer 210.

In some embodiments, the materials and forming methods of the first protective layer 210 and/or the second protective layer 220 may be the same or different from those of the inorganic protective layer 200. In some embodiments, the first protective layer 210 and the second protective layer 220 may comprise the same or different materials. In some embodiments, the first protective layer 210 is dense because the first protective layer 210 is formed by an atomic layer deposition process. The second passivation layer 220 is formed by a sol-gel process, so that the second passivation layer 220 is relatively loose with respect to the first passivation layer 210. Accordingly, the thickness 210t of the first protective layer 210 may be less than the thickness 220t of the second protective layer 220.

In some embodiments, the thickness 210t of the first protective layer 210 may be greater than or equal to 1nm to less than or equal to 100nm. For example, the thickness 210t of the first protection layer 210 may be 1nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, a value or a range of values between the foregoing values, but the disclosure is not limited thereto. In some embodiments, if the thickness 210t of the first protection layer 210 is greater than 100nm, the light-emitting efficiency of the quantum dot 120 may be reduced, and if the thickness 210t of the first protection layer 210 is less than 1nm, moisture and/or oxygen may not be effectively blocked.

In some embodiments, the thickness 220t of the second protective layer 220 may be greater than or equal to 10nm to less than or equal to 500nm. For example, the thickness 220t of the second protection layer 220 may be 10nm, 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, a value or a range of values between the foregoing values, but the disclosure is not limited thereto. In some embodiments, if the thickness 220t of the second protection layer 220 is greater than 500nm, the light-emitting efficiency of the quantum dots 120 may be reduced, and if the thickness 220t of the second protection layer 220 is less than 10nm, moisture and/or oxygen may not be effectively blocked.

In some embodiments, the sum of the thickness 210t of the first protection layer 210 and the thickness 220t of the second protection layer 220 may be less than or equal to 500nm, so as to avoid the problem of poor light-emitting efficiency and reduced carrier transport efficiency of the quantum dot caused by excessive thickness. In some embodiments, the first protective layer may include a plurality of sub-layers, and the sum of the thicknesses of the plurality of sub-layers and the thickness 220t of the second protective layer 220 is less than or equal to 500nm.

In some embodiments, the density (density) of the first protection layer 210 may be greater than the density of the second protection layer 220, e.g., the number of oxide molecules per unit volume of the first protection layer 210 is greater than the number of oxide molecules per unit volume of the second protection layer 220. In some embodiments, the density of the first protective layer 210 may be greater than 1g/cm ³ and the density of the second protective layer 220 may be less than 1g/cm ³. Thus, the first protection layer 210 may be a dense oxide layer to provide a protection effect in close proximity to the quantum dots 120.

In some embodiments, the first protective layer 210 is an inorganic oxide layer formed by an atomic layer deposition process, and the second protective layer 220 is an inorganic oxide layer formed by a sol-gel process. The second protective layer 220 has a porosity (porosity) that is greater than the porosity of the first protective layer 210, where porosity is defined herein as the ratio of the volume of the pores to the total volume of the material. Therefore, the first protection layer 210 can effectively block moisture and/or oxygen, and the second protection layer 220 captures moisture and oxygen in the environment by the holes, so that the moisture and oxygen in the environment are difficult to contact with the quantum dots 120. In addition, since the second protection layer 220 has a larger porosity, the second protection layer 220 has better toughness and is not easy to crack, so as to provide buffering and protect the quantum dots 120.

Fig. 4 is a schematic perspective view illustrating a quantum dot composite structure 3 according to some embodiments of the present disclosure. As shown in fig. 4, in some embodiments, the first protective layer 210 may include multiple sublayers. In some embodiments, the number of sub-layers may be any natural number, for example, 1-5 layers, although the disclosure is not limited thereto. For example, when the number of the sub-layers is 1, the first protection layer 210 is a single-layer structure, and when the number of the sub-layers is greater than 1, the first protection layer 210 is a multi-layer structure. For ease of illustration, fig. 4 shows the number of sub-layers of the first protection layer 210 as 2, i.e., the first protection layer 210 includes a first sub-layer 210a and a second sub-layer 210b, but the disclosure is not limited thereto. In some embodiments, the first sub-layer 210a may be disposed on the glass particles 100, the second sub-layer 210b may be disposed on the first sub-layer 210a, and the second protective layer 220 may be disposed on the second sub-layer 210 b. In addition, in order to avoid the problems of poor light-emitting efficiency and reduced carrier transmission efficiency of the quantum dots caused by excessive thickness, the sum of the thicknesses of the first protective layer and the second protective layer is less than or equal to 500nm. In some embodiments, the sublayers may be formed of the same or different materials. For example, the sub-layer may comprise silicon oxide, aluminum oxide, or a combination thereof.

Examples of quantum dot composite structures are provided below and in table 1, following the above. Examples 1 and 2 are examples of the quantum dot composite structure 2 shown in fig. 3 and the quantum dot composite structure 3 shown in fig. 4, respectively.

TABLE 1

For example, in example 1, about 2.5g of the glass particles 100 subjected to the particle size selection process were placed in an atomic layer deposition apparatus, and a dense silicon dioxide layer was synthesized as the first protective layer 210 on the surface of the glass particles 100 subjected to the particle size selection process by reacting tris (dimethylamino) silane (tris (dimethylamino) silane, TDMAS) with ozone at 80 ℃. Next, about 2.0g of the glass particle 100 modified by the atomic layer deposition process was placed in 30mL of n-hexane (n-hexane), 20mL of Polydimethylsiloxane (PDMS), 4mL of tetraethoxysilane (tetraethylorthosilicate, TEOS), 2mL of dibutyltin dilaurate (dibutyltin dilaurate, DBTL) and stirred for about 30 minutes, and 0.020g of azobisisobutyronitrile (2, 2' -azobis (2-methylpropionitrile), AIBN) was added as an initiator for the reaction, and refluxed at 85 ℃ for 4 hours, so that a loose and thick silica layer was synthesized as a second protective layer 220 on the surface of the glass particle 100 modified by the atomic layer deposition process, thereby obtaining the quantum dot composite structure 2 shown in example 1. Wherein the product can be further washed with n-hexane (n-hexane) and dried at 60deg.C. For example, the remaining steps are the same, and 2 sub-layers of the first protection layer 210 are formed by 2 cycles of atomic layer deposition process, so as to obtain the quantum dot composite structure 3 shown in example 2. Wherein 2 cycles of the atomic layer deposition process may use different precursors to form different sub-layers of the first protective layer 210. For example, the precursor may further include trimethylaluminum (trimethylaluminum, TMA) to form aluminum oxide. In some embodiments, the first protective layer 210 may include a first sub-layer 210a of SiO ₂ and a second sub-layer 210b of Al ₂O₃. For example, after forming the first sub-layer 210a of the first protective layer 210 with TDMAS and ozone, aluminum oxide (Al ₂O₃) is synthesized as the second sub-layer 210b on the surface of the first sub-layer 210a by reacting TMA with water at 80 ℃ for modification by an atomic layer deposition process to provide a dense aluminum oxide layer. In some embodiments, regarding the process parameters associated with the formation of alumina as the second sub-layer 210b by the atomic layer deposition method, the quartz tube rotation speed may be set to 2rpm, the reaction temperature may be 80 ℃, and the carrier gas flow may be 5sccm. Then, the following step (1) is executed: TMA was injected into the quartz tube for 0.015 seconds, and after 20 seconds of rest, TMA was injected again for 0.015 seconds, and step (1) was repeated 3 times. After that, step (2) is performed: spraying the water vapor into the quartz tube for 0.015 seconds, standing for 20 seconds, spraying the water vapor for 0.015 seconds again, and repeating the step (2) for 3 times. Repeating the steps (1) and (2), and executing the steps (1) and (2) once is repeated 1 time. For example, the coating thickness of the aluminum oxide (Al ₂O₃) as the second sub-layer 210b on the first sub-layer 210a may be adjusted by repeating 40 to 100 times, such as 60 times of the steps (1) and (2). Then, the second protective layer 220 may be formed on the first protective layer 210 (including the first sub-layer 210a and the second sub-layer 210 b) in the manner described above.

Hereinafter, the analysis is performed in example 1, but the disclosure is not limited thereto, and example 2 and other matters described herein may also have the effect of the subsequent analysis.

Fig. 5 is a graph showing X-ray diffraction analysis (XRD) (instrument brand and model: bruker D2 Phaser Diffractometer) at various stages in a method of forming a quantum dot composite structure 2, according to some embodiments of the present disclosure. The XRD patterns of CsPbBr ₃ standard, glass particles before the particle size screening process, glass particles after the atomic layer deposition process, and glass particles after the sol-gel process are shown therein. Wherein the glass particles after the sol-gel process represent glass particles after having undergone an atomic layer deposition process and after having undergone a sol-gel process.

As shown in fig. 5, the main crystal phase of each stage is green all-inorganic perovskite CsPbBr ₃, and diffraction peaks are present at 15 ° (degrees) to 30 ° before the particle size selection process, after the particle size selection process, and after the atomic layer deposition process, which can be confirmed that CsPbBr ₃ exists. However, after the sol-gel process, since the surface silicon dioxide layer as the second protective layer 220 is thicker, the diffraction signal is mainly the second protective layer 220, so that the diffraction signal of the CsPbBr ₃ crystal is not easy to peep, thereby confirming that the second protective layer 220 is successfully formed.

Fig. 6 is a fluorescence spectrum (instrument brand and model: edinburgh Instrument FLS1000 Photoluminescence Spectrometer) showing various stages in a method of forming a quantum dot composite structure 2, according to some embodiments of the present disclosure. As shown in fig. 6, the emission peak of the glass particles before the particle size selection process was 525nm, the quantum dot efficiency was 45.6% and the half width was 24.6nm, the emission peak of the glass particles after the particle size selection process was 528nm, the quantum dot efficiency was 49.2% and the half width was 24.0nm, the emission peak of the glass particles after the atomic layer deposition process was 530nm, the quantum dot efficiency was 45.9% and the half width was 23.6nm, and the emission peak of the glass particles after the sol-gel process was 530nm, the quantum dot efficiency was 44.0% and the half width was 23.6nm. As a result, the fluorescence emission peaks at each stage are located at 525 nm-530 nm without significant red shift, and the half-width of the emission peaks is not significantly changed, which means that the temperature of the atomic layer deposition process and the sol-gel process does not damage CsPbBr ₃ quantum dots.

Fig. 7 is a diagram of hydrophobic test images showing stages in a method of forming a quantum dot composite structure, according to some embodiments of the present disclosure. Wherein, part (a) of fig. 7 is an image of glass particles immersed in distilled water after a particle size selection process, and part (b) of fig. 7 is an image of glass particles immersed in distilled water after a sol-gel process. Fig. 7 (a) partially shows rapid mass sedimentation of glass particles to the bottom of the bottle after immersion in water, and fig. 7 (b) partially shows floating of glass particles of example 1 on the water surface, representing that the quantum dot composite structure 2 of example 1 has high hydrophobicity and high water resistance.

Fig. 8 is a diagram of hydrophobic test images showing stages in a method of forming a quantum dot composite structure, according to some embodiments of the present disclosure. Wherein, part (a) and part (b) of fig. 8 are respectively an image taken under visible light on the day when glass particles subjected to a sol-gel process are immersed in distilled water and an image taken under visible light after being irradiated with ultraviolet light on the day, and part (c) and part (d) of fig. 8 are respectively an image taken under visible light after glass particles subjected to a sol-gel process are immersed in distilled water for one day and an image taken under visible light after being irradiated with ultraviolet light after one day. Wherein, after irradiating with ultraviolet light for 30 seconds, shooting is performed. As shown in fig. 8 (c) and (d), after immersing in distilled water for one day, the quantum dot composite structure still floats on the water surface without significant change in appearance and color, and can emit intense fluorescence after being irradiated by ultraviolet light, which means that the quantum dot composite structure 2 of example 1 can provide high hydrophobicity and high water resistance to provide excellent protection effect of internal CsPbBr ₃ quantum dots.

Fig. 9-12 are image diagrams of Scanning Electron Microscopes (SEM) (instrument brand and model: JSM-6510 scanning electron microscope from JEOL corporation) respectively showing stages in a method of forming a quantum dot composite structure, according to some embodiments of the present disclosure. Wherein fig. 9 shows SEM images of different dimensions before the particle size screening process, fig. 10 shows SEM images of different dimensions after the particle size screening process, fig. 11 shows SEM images of different dimensions after the atomic layer deposition process, and fig. 12 shows SEM images of different dimensions after the sol-gel process.

Fig. 9 shows a broader particle size distribution and more impurity deposition on the particle surface. FIG. 10 shows that the particle surface is cleaner and the particle size distribution is more concentrated after the particle size selection process. The SEM images of fig. 11 and 12 do not clearly show the thickness of the first and second passivation layers, so the first and second passivation layers 210 and 220 will be further analyzed by infrared absorption spectroscopy and transmission electron microscopy.

Fig. 13 is an infrared light absorption Spectrum (instrument brand and model: PERKIN ELMER Spectrum Two FT-IR L160000F) showing various stages in a method of forming a quantum dot composite structure, according to some embodiments of the present disclosure. Wherein, fig. 13 (a) partially shows the absorption spectrum of the glass particles after the particle size screening process, and fig. 13 (b) partially shows the absorption spectrum of the quantum dot composite structure after the sol-gel process.

As shown in FIG. 13, since the glass particles include CsPbBr ₃ perovskite quantum dots, the absorption signals of the B-O bond and the Si-O bond can be measured. The quantum dot composite structure after the atomic layer deposition process and the sol-gel process comprises a silicon dioxide layer, and the silicon dioxide layer is formed by the reaction polymerization of polydimethylsiloxane and tetraethoxysilane, so that the absorption signals of C-H bonds, C-O bonds, si-O bonds and the like can be measured. FIG. 13 (a) shows, in part, the vibration (vibration) absorption of units 704cm ^-1、1004cm^-1 and 1391cm ^-1 having B-O-B bonds, si-O-Si bonds, and [ BO ₃ ], respectively. FIG. 13 (b) shows that the absorption peaks are respectively present at 800cm ^-1、1021～1097cm^-1、1262cm^-1、2963cm^-1. Wherein the absorption peak at 800cm ^-1 represents the vibration absorption of Si-O bond, the absorption peak at 1021-1097 cm ^-1 represents the vibration absorption of Si-O-Si bond and the tensile vibration (STRETCHING VIBRATION) absorption of C-O bond, the absorption peak at 1262cm ^-1 represents the tensile vibration absorption of the C-O bond and the absorption peak at 2963cm ^-1 represents the tensile vibration absorption of the C-H bond. Thus, fig. 13 (b) partially demonstrates that the quantum dot composite structure 2 includes CsPbBr ₃ quantum dots 120 and a silicon dioxide protective layer 200.

Fig. 14 and 15 are Transmission Electron Microscope (TEM) (instrument brand and model: JEM 2100F transmission electron microscope from JEOL company) images respectively showing various stages in a method of forming a quantum dot composite structure according to some embodiments of the present disclosure. Fig. 14 shows different-scale TEM images after an atomic layer deposition process, and fig. 15 shows different-scale TEM images after a sol-gel process.

As shown in part (a) of fig. 14, a large number of CsPbBr ₃ perovskite quantum dots 120 (dark black particles) are dispersed in a glass substrate 110 (black block), and a thin layer of silica (gray block) coated flat is provided outside the glass substrate 110 as a first protective layer 210. As shown in part (b) of fig. 14, the thickness 210t of the first protective layer 210 is about 4.5nm. As shown in fig. 15 (a), nano-scale thin film silicon dioxide (gray scale block) is further coated as a second protective layer 220. As shown in part (b) of fig. 15, the thickness 220t of the second protective layer 220 is about 11nm. Thus, fig. 15 (b) partially demonstrates that the quantum dot composite structure 2 includes the CsPbBr ₃ quantum dots 120, the first protective layer 210, and the second protective layer 220.

The quantum dot composite structure of the present disclosure can be applied to various light emitting devices, such as a light emitting diode device, a lighting device, a backlight module of a display, or pixels of a display. Taking a light emitting diode device as an example, fig. 16 is a schematic diagram of a light emitting diode device according to some embodiments of the disclosure. In some embodiments, the light emitting diode device 300 includes a base 310, a light emitting diode chip 320, a wavelength conversion layer 330, and a reflective wall 340. The base 310 has a positive electrode 310a and a negative electrode 310b, the upper surface of the base 310 has a die bonding region 310s, and the reflective wall 340 is disposed on the base 310 and surrounds the die bonding region 310s and defines a receiving space 312. The led chip 320 is disposed in the accommodating space 312 and is fixed on the die bonding region 310s of the base 310. The light emitting diode chip 320 may emit blue light or UV light. In addition, the light emitting diode chip 320 may be a small-sized light emitting diode chip, such as a sub-millimeter light emitting diode chip (MINI LED CHIP), a micro light emitting diode chip (micro LED chip). The led chip 320 may be mounted using a face-up (face-up) configuration as shown in fig. 16, or may be mounted using other flip chip configurations as desired. The wavelength conversion layer 330 is disposed on the light emitting surface of the led chip 320, and the wavelength conversion layer 330 includes transparent adhesive 332 mixed with the quantum dot composite structure 2 shown in fig. 2 or the quantum dot composite structure 3 shown in fig. 3 of the present disclosure. For example, the material of the transparent colloid 332 may be one of Polydimethylsiloxane (PDMS), epoxy (epoxy), silicone (silicone), or a combination of two or more materials.

According to some embodiments of the present disclosure, the wavelength conversion layer 330 may also mix other phosphors or may mix with the quantum dot composite structure 2 (or 3) emitting different colors according to color requirements, in addition to the quantum dot composite structure 2 or 3 of the present disclosure. Taking the led device 300 as an example, the led chip 320 emits blue light, and the wavelength conversion layer 330 includes the green quantum dot composite structure 2 and the red quantum dot composite structure 2. Taking the led device 300 as an example, the led chip 320 emits UV light, and the wavelength conversion layer 330 includes a blue quantum dot composite structure 2, a green quantum dot composite structure 2, and a red quantum dot composite structure 2. In some embodiments, the blue light quantum dot composite structure 2 is a blue all-inorganic perovskite quantum dot CsPb (Cl _aBr_1-a)₃ and 0<a.ltoreq.1. In some embodiments, the quantum dot 120 of the green light quantum dot composite structure 2 is a green all-inorganic perovskite quantum dot CsPb (Br _1-bI_b)₃ and 0.ltoreq.b <0.5. In some embodiments, the quantum dot 120 of the red all-inorganic perovskite quantum dot composite structure 2 is a red all-inorganic perovskite quantum dot CsPb (Br _1-bI_b)₃ and 0.5.ltoreq.b.ltoreq.1).

Furthermore, the led device can be in various forms, and is not limited to the led device 300 shown in fig. 16. FIG. 17 is a schematic diagram of another LED device. The light emitting diode device 400 includes a light emitting diode chip 420, a wavelength conversion layer 430. The led chip 420 is in a flip-chip type, and the wavelength conversion layer 430 includes the quantum dot composite structure 2 (or 3) and transparent adhesive material, and the wavelength conversion layer 430 conformally encapsulates the upper surface and the sidewalls of the led chip 320. In some embodiments, the material of wavelength-converting layer 430 is the same as or different from the material of wavelength-converting layer 330.

In summary, according to some embodiments of the present disclosure, a quantum dot composite structure including a protective layer and a method for forming the same are provided, so that stability of the quantum dot can be further improved. In detail, even though the quantum dots are disposed in the glass matrix, the glass matrix exposes at least a portion of the exposed surface of the quantum dots, thereby causing the quantum dots to be deteriorated by environmental factors. Therefore, the inorganic protective layer is arranged to cover the exposed surface of the quantum dot, so that the capability of the quantum dot for resisting environmental factors, such as water vapor resistance and oxygen resistance, is improved, and the luminous efficacy of the quantum dot is maintained. Furthermore, in some embodiments, the protection layer may further include a first protection layer and a second protection layer. The ability of the quantum dot to resist environmental factors is enhanced by different combinations of parameters of the first and second protective layers, such as density, crystallinity, thickness, porosity, and material type.

The components of the embodiments of the present disclosure may be mixed and matched at will without departing from the spirit or conflict of the present disclosure. Furthermore, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification, which will be readily apparent to those of ordinary skill in the art from the present disclosure, unless otherwise indicated herein, such that the process, machine, manufacture, composition of matter, means, methods and steps described in the specification are performed with essentially the same function or result in essentially the same way as described herein. Accordingly, the scope of the present application includes manufacture, machine, manufacture, composition of matter, means, methods and steps described in the specification. Not all of the objects, advantages, and/or features disclosed herein are required to be achieved by any one embodiment or claim of the present disclosure.

The foregoing outlines several embodiments so that those skilled in the art may better understand the aspects of the embodiments of the present disclosure. It should be appreciated by those skilled in the art that other processes and structures may be devised or modified from those described herein that will fall within the scope of the embodiments described herein. It should also be understood by those skilled in the art that such equivalent processes and structures do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the present disclosure.

[ Symbolic description ]

1,2, 3-Quantum dot composite Structure

100 Glass particles

100'

110 Glass substrate

120 Quantum dots

120S exposed surface

200 Protective layer

200T,210t,220t thickness

210 First protective layer

210A first sub-layer

210B second sub-layer

220 Second protective layer

300,400 Light emitting diode device

310 Base

310A positive electrode

310B negative electrode

310S solid crystal area

312 Accommodating space

320,420 Light emitting diode chip

330,430 Wavelength converting layer

332 Transparent adhesive material

340 Reflecting wall

D,100d diameter

Claims

1. A quantum dot composite structure, comprising:

A glass particle comprising a glass matrix and a plurality of quantum dots in the glass matrix, and the glass matrix exposes an exposed surface of at least one of the plurality of quantum dots; and

And an inorganic protective layer which is arranged on the glass particles and covers the exposed surface.

2. The quantum dot composite structure of claim 1, wherein the inorganic protective layer has a thickness of greater than or equal to 1nm to less than or equal to 500nm.

3. The quantum dot composite structure of claim 1, wherein the inorganic protective layer comprises an inorganic oxide.

4. The quantum dot composite structure of claim 1, wherein the glass matrix comprises phosphosilicate glass (phosphosilicate glass), tellurite glass (tellurite glass), borosilicate glass (borosilicate glass), borogermanate glass (borogermanate glass), or any combination thereof.

5. The quantum dot composite structure of claim 1, wherein the inorganic protective layer comprises:

A first protective layer covering the glass particles and in direct contact with the exposed surface; and

The second protection layer is arranged on the first protection layer, and the first protection layer is arranged between the glass particles and the second protection layer.

6. The quantum dot composite structure of claim 5, wherein the thickness of the first protective layer is less than the thickness of the second protective layer.

7. The quantum dot composite structure of claim 5, wherein the first protective layer has a density greater than a density of the second protective layer.

8. The quantum dot composite structure of claim 5, wherein the first protection comprises a plurality of sublayers.

9. The quantum dot composite structure of claim 5, wherein the first protective layer conforms to the shape of the glass particle.

10. The quantum dot composite structure of claim 5, wherein the first protective layer is an inorganic oxide layer formed by an atomic layer deposition process and the second protective layer is an inorganic oxide layer formed by a sol-gel process.

11. The quantum dot composite structure of claim 1, wherein the plurality of quantum dots have a luminescence wavelength of greater than or equal to 300nm to less than or equal to 800nm.

12. The method for forming the quantum dot composite structure is characterized by comprising the following steps of:

Providing a glass particle, wherein the glass particle comprises a plurality of quantum dots;

forming a first protection layer on the glass particles through an atomic layer deposition process so that the first protection layer conformally coats the glass particles; and

A second protective layer is formed on the first protective layer through a sol-gel process, so that the second protective layer covers the first protective layer.

13. The method of claim 12, wherein the reaction temperature of the atomic layer deposition process and the sol-gel process is greater than or equal to 60 ℃ to less than or equal to 180 ℃.

14. The method of claim 13, wherein the atomic layer deposition process reacts tris (dimethylamino) silane (TDMAS) with ozone at a temperature greater than or equal to 75 ℃ to less than or equal to 90 ℃ to form the first protective layer.

15. The method of claim 13, wherein the sol-gel process uses Azobisisobutyronitrile (AIBN) as an initiator, and the second protective layer is formed by reacting Polydimethylsiloxane (PDMS), tetraethoxysilane (TEOS), dibutyltin dilaurate (dibutyltin dilaurate, DBTL) at a temperature of 75 ℃ or more and 90 ℃ or less.

16. The method of forming of claim 12, wherein providing the glass particles further comprises:

Forming a glass block by a melting-quenching process;

Performing a polishing process to break the glass block into the glass particles; and

A particle size screening process is performed to screen out the glass particles having an average diameter of 20 μm or more and 50 μm or less.

17. The method of forming of claim 12, wherein a thickness of the first protective layer is less than a thickness of the second protective layer.

18. The method of forming of claim 12, wherein a total thickness of the first protective layer and the second protective layer is less than or equal to 500nm.

19. The method of forming of claim 12, wherein a density of the first protective layer is greater than a density of the second protective layer.

20. The method of forming of claim 12, wherein forming the first protective layer comprises forming a plurality of sub-layers.